Esther Turnhout is a Professor at the Forest and Nature Conservation Policy Group of Wageningen Universiteit, The Netherlands. Her research program, 'The Politics of Environmental Knowledge', includes research into the different roles experts play at the science-policy interface, the political implications of policy-relevant environmental knowledge and the interaction between science, society and citizens. Willemijn Tuinstra works as an independent advisor on knowledge development for environmental policy. She advises research institutes and civil servants on procedural aspects of stakeholder participation, scenario development and dealing with uncertainties. She has been involved in projects for the European Environment Agency and the International Institute for Applied Systems Analysis. Willem Halffman is an associate professor in the Faculty of Science at Radboud Universiteit Nijmegen. His work focuses on studying how scientific knowledge is validated and how scientists advise public decision making. He has over twenty years' experience teaching science and society courses to natural scientists.